1. Field of the Invention
The present invention relates to a solid-state imaging device, a manufacturing method and a design method thereof, and electronic equipment, and specifically, to a solid-state imaging device having color filters of R (red), green (G), and blue (B), a manufacturing method and a design method thereof, and electronic equipment.
2. Background Art
Electronic equipment such as digital video electronic equipment or digital still electronic equipment has a solid-state imaging device including a CCD (Charge Coupled Device) image sensor and a CMOS (Complementary Metal-Oxide-Silicon Transistor) image sensor, for example.
In the solid-state imaging device, plural pixels are arranged in a matrix in the horizontal direction and the vertical direction on a semiconductor substrate, and form a light receiving surface. On the light receiving surface, sensors as photoelectrically conversion parts such as photodiodes are provided for the respective pixels.
On the light receiving surface, a light focusing structure for focusing light according to an object image on the sensors of the respective pixels is formed, signal charge is generated by receiving the light according to the object image and photoelectrically converting the received light, and thereby, pixel signals are obtained.
In the CCD, CMOS image sensors in related art, the light entering the sensor part is photoelectrically converted by the photodiode, the incident light is converted into electric charge, and a video signal is obtained. Such a device has a structure in which the light entering in a fixed exposure time is converted into electric charge and accumulated.
Since the amount of accumulated electric charge is finite, for example, when strong light enters, the electric charge is saturated and a white and black gradation becomes insufficient. That is, there is a range of an amount of incident light for the solid-state imaging device to obtain appropriate output signals, and the range is very narrow compared to that of an imaging target.
Accordingly, a technology of expanding the dynamic range of the solid-state imaging device is desired.
As dynamic range expansion technologies in related art, Non-Patent Document 1 (2005 IEEE Workshop on Charge-Coupled Devices and Advanced Image Sensors P.169, P.173) discloses a technology of changing intervals of photoelectric conversion in response to amounts of incident light. Further, Patent Document 1 (JP-A-2008-167004) discloses a method of setting gain in response to amounts of incident light.
Furthermore, Patent Document 2 (JP-A-2006-333439) discloses a solid-state imaging device having a light blocking member that blocks a photoelectric conversion part from light and an actuator that drives the light blocking member using MEMS.
In addition to the methods of expanding the dynamic range by the device configuration, there are proposals to realize the dynamic range expansion technology using materials.
Further, Patent Document 3 (JP-A-1-248542) and Patent Document 4 (JP-A-10-65129) disclose methods of expanding a dynamic range by applying a material on a surface of glass of a case part of a solid-state imaging device or inserting a material between the glass surface and the solid-state imaging device for photochromic control.
Furthermore, Patent Document 5 (JP-A-1-236649) discloses a method of expanding a dynamic range by forming a film of a material at the upstream of the sensor part for photochromic control.
Moreover, Patent Document 6 (JP-A-4-65163) discloses a method of applying a photochromic reaction material to the outer side of a photodiode.
As a problem hard to be solved in related art technologies, there are time lags at moving picture imaging and continuous imaging.
That is, in a technique using a readout system, time lags are caused at plural readouts and long and short electric charge accumulation, and, in a technique using a mechanical shutter, time lags are caused depending on positions. Accordingly, it may be impossible to completely remove unnaturalness as images.
On the other hand, regarding the technology of expanding the dynamic range by materials, there are problems that transmittance has wavelength dependence and a reaction rate of the photochromic reaction does not satisfy specifications determined by the signal processing speed of the existing solid-state imaging device. Thus, it has been difficult to use the technology for the solid-state imaging device.